Thank you faceplant for your answer.
However I'm not sure to understand what you mean. In fact why I am able to read in the /sys/bus/iio/devices/iio:device1/in_voltage0_raw file the voltage if I run a code with mraa first?
And why the guys from emutexlabs have wrote that after all the commands they wrote we should be able to read the value in /sys/bus/iio/devices/iio:device1/in_voltage0_raw if it can't be possible without creating an interface?
http://www.emutexlabs.com/project/215-intel-edison-gpio-pin-multiplexing-guide -> example 3